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Relationship between oscillatory volume and oscillatory pressure in neonatal high-frequency oscillatory ventilators: an in vitro study


Objective We analysed the relationship between oscillatory volume (VOSC) and pressure amplitude (ΔP) in six neonatal high-frequency oscillatory (HFO) ventilators and related it to (1) the accuracy of VOSC and ΔP measurements and (2) the maximal delivered ΔP.

Design In vitro study.

Setting Neonatal intensive care unit.

Interventions Ventilators tested were VN800 (Dräger), Servo-n (Maquet Getinge), SensorMedics 3100A (Vyaire Medical), Fabian HFOi (Vyaire Medical), SLE6000 (SLE UK) and Humming Vue (Metran). We changed various settings and mechanical characteristics of the test lung to mimic preterm and term conditions.

Main outcome measures For each condition, we measured VOSC and ΔP. We assessed the accuracy of the VOSC and ΔP measurements versus a reference measurement system using linear regression and Bland-Altman analysis. We evaluated the maximum delivered ΔP at different oscillatory frequencies.

Results We observed large variability between machines in the ΔP displayed at any target VOSC. Most ventilators over-read ΔP with errors up to 30 cmH2O or 60%. The error in the measurement of VOSC was up to ±2 mL or ±30%. We observed high variability in the accuracy of ΔP and VOSC measurements; the SLE6000 committed the lowest errors in ΔP measurements and the Fabian HFOi in VOSC. The maximum delivered ΔP varied depending on the ventilator, being maximal for the Humming Vue, followed by the SLE6000 and SensorMedics 3100A.

Conclusions The variability in the relationship between VOSC and ΔP among HFO ventilators is largely explained by the variable accuracy in ΔP and VOSC measurement. Different ventilators also exhibit important differences in the maximal generated ΔP.

  • Intensive Care Units, Neonatal
  • Technology
  • Respiratory Medicine

Data availability statement

Data are available upon reasonable request. All data generated or analysed during this study are included in this article.

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